Re: verbose oops possible?

Richard B. Johnson (root@chaos.analogic.com)
Tue, 20 Apr 1999 09:54:23 -0400 (EDT)


On Tue, 20 Apr 1999, Jeff Garzik wrote:

> Is there a patch I can apply, or switch I can flip, to have the kernel
> oops be more verbose?
>
> I don't mind the memory wasted by loading a symbol table into memory, if
> the oops output could look more like ksymoops output...
>
> (i'm on an alpha, if it matters)
>

The problem is not a symbol table. It is that you can't use any kernel
resources after an oops because they probably got corrupted, or at
least must be assumed to have been corrupted. Even printk is suspect
after an oops because a runaway pointer could have even corrupted code.

Note that within the kernel, there is no protection. The kernel can
destroy anything including itself. Often it is only when the page-fault
handler tries to fault in non-existent pages that the kernel knows
anything is wrong.

You probably have noticed that sometimes an oops doesn't seem to make
sense. You decipher bad op-codes (0xff, 0xff, 0xff), strange memory
^^^^^^^^^^^^^^ no memory here.
locations (0x20202020), etc., This is because much corruption occurred
^^^^^^^^^^ text (spaces).
before the page-fault trap.

Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.2.6 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.

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